The present invention is generally directed to inkjet printers. More particularly, the invention is directed to an integrated circuit for an ink jet printhead for selectively addressing and activating printing elements according to a multi-dimensional addressing scheme.
Hardware and software limitations constrain current inkjet printers. For example, the number of available inputs and outputs limit the operation of an inkjet printhead""s integrated circuitry to effectuate a printing operation to print an image onto a print medium. The printhead""s integrated circuit limitations have a corresponding limiting effect on overall printing operations. Thus, there is a need for inkjet printers and printing techniques which overcome these drawbacks and limitations.
The foregoing and other needs are met by an improved printhead drive scheme for activating printing elements on a printhead of an ink jet printer. In one aspect of the invention, providing first, second, third, and fourth control signals to a printhead control circuit activates one or more firing resistors, herein termed heaters, thereby energizing adjacently disposed ink to print an image on a print medium.
Providing an additional ground switching device, such as a field effect transistor, in the printhead control circuit that electrically connects each source of each power transistor to a drain of a ground switching device provides an additional dimension for the printer to address inkjet printhead nozzles. Activating one or more ground switching devices connects one or more corresponding heaters to ground.
Thus, the invention provides an additional dimension for addressing a printhead. A one for one match is not required between the one or more ground switching devices and the resistive heaters. For example, two or more of the heaters could be connected in parallel to each other, and the parallel heaters could be connected in series with one more of the ground switching devices.
In another aspect, the addition of the ground switching devices allows a fixed voltage rail on the high sides of the heaters. A fixed voltage rail allows printer driver simplification, the driver providing the switching to the high side of the heaters for each fire while maintaining a reduced input/output architecture.
One advantage of the invention is that the additional addressing dimension may be used to prevent the firing of all heaters of the printhead. This xe2x80x9cchip-selectxe2x80x9d feature allows sharing the other address lines between different printheads, monochrome and color for example, using the additional addressing dimension to determine which printhead is printing.
A method is disclosed for activating a printing element within an array of printing elements on a printhead of an inkjet printer. The printhead includes a plurality of printing elements, power switching devices, pass switching devices, and one or more ground switching devices. A plurality of subsets of printing elements and associated pass switching devices are defined within a plurality of groups of printing elements and associated pass switching and power switching devices. The method provides a subset selection signal to the pass switching devices and power switching devices of a selected one of the subsets to thereby select a subset of printing elements in the array of printing elements based on the subset selection signal.
An address signal is provided to a selected subset of the pass switching devices to thereby select a one or more printing elements based on the address signal, and a heater select signal is provided to one or more of the ground switching devices. The method also provides a primitive signal to a select one of the groups of printing elements on the printhead, and activates a selected printing element within the select group based on the primitive signal and the heater select signal.
An integrated circuit is provided for use in an ink jet printer having a printer controller for generating print signals and a printhead for generating a printed image on a print medium. The integrated circuit includes a plurality of printing elements arranged in selectable groups for printing the image on the print medium. The circuit includes a plurality of power switching devices, each coupled to a corresponding one of the printing elements, a plurality of pass switching devices, each coupled to a corresponding one of the power switching devices, and one or more ground switching devices coupled to one or more of the power switching devices.
The circuit has p number of first control lines, each coupled to a corresponding one of the selectable groups of printing elements. Each first control line provides the first control signal to one or more of the selectable groups of printing elements, thereby selectively enabling activation of one or more of the selectable groups of the printing elements. The circuit has q number of second control lines, each coupled to a corresponding selectable subset of power switching devices and pass switching devices within one or more of the selectable groups of printing elements. Each second control line provides the second control signal to the corresponding selectable subset of power switching devices and pass switching devices, the second control lines for selectively enabling activation of the corresponding subset of power switching devices and pass switching devices within the one or more selectable groups.
The circuit also includes a number of third control lines, each coupled to corresponding pass switching devices within each subset of printing elements. The third control lines provide the third control signal to the corresponding selectable subset of pass switching devices, the third control signal for selectively enabling activation of one of the printing elements within the corresponding selectable subset. H number of fourth control lines are coupled to the one or more of the ground switching devices. The fourth control lines provide the fourth control signal to the one or more ground switching devices, selectively activating the one or more of the ground switching devices to connect the one or more power switching devices to ground, and thereby activating a selected printing element within the selected subset of printing elements.